The environmental protection problem is now one of the most important issues. In this connection, many sewage purification facilities have recently and will nearly been installed all over the world and excess sludge produced in these facilities has to be handled economically due to the uprising fuel cost. Further, the exhaust gas discharged from sludge burning apparatus must been cleaned by removing dust and by minimizing SOx and/or NOx.
This invention was made to cope with these problems.